Module « sqlalchemy.orm »

Fonction with_parent - module sqlalchemy.orm

Signature de la fonction with_parent

def with_parent(instance, prop, from_entity=None) 

Description

with_parent.__doc__

Create filtering criterion that relates this query's primary entity
    to the given related instance, using established
    :func:`_orm.relationship()`
    configuration.

    E.g.::

        stmt = select(Address).where(with_parent(some_user, Address.user))


    The SQL rendered is the same as that rendered when a lazy loader
    would fire off from the given parent on that attribute, meaning
    that the appropriate state is taken from the parent object in
    Python without the need to render joins to the parent table
    in the rendered statement.

    The given property may also make use of :meth:`_orm.PropComparator.of_type`
    to indicate the left side of the criteria::


        a1 = aliased(Address)
        a2 = aliased(Address)
        stmt = select(a1, a2).where(
            with_parent(u1, User.addresses.of_type(a2))
        )

    The above use is equivalent to using the
    :func:`_orm.with_parent.from_entity` argument::

        a1 = aliased(Address)
        a2 = aliased(Address)
        stmt = select(a1, a2).where(
            with_parent(u1, User.addresses, from_entity=a2)
        )

    :param instance:
      An instance which has some :func:`_orm.relationship`.

    :param property:
      String property name, or class-bound attribute, which indicates
      what relationship from the instance should be used to reconcile the
      parent/child relationship.

      .. deprecated:: 1.4 Using strings is deprecated and will be removed
         in SQLAlchemy 2.0.  Please use the class-bound attribute directly.

    :param from_entity:
      Entity in which to consider as the left side.  This defaults to the
      "zero" entity of the :class:`_query.Query` itself.

      .. versionadded:: 1.2